Most will cache the writes and be in control of power down/sleep so that data writes to SD will complete. If you bypass the FAT filing system by writing to empty blocks, then the filing system has no idea that blocks have been used and no idea where you logged data is.
Sd secure erase Pc#
Edit: most commercial data loggers will use the FAT filing system, otherwise you would not be able to access the logs on a PC as a file. Whether they are actually blank or not depends on the particular implementaion of the FAT filing system. Hence it also knows which blocks are not in use. It tracks what is in use and which blocks they are in. As far as being able to control which blocks are in use and need erasing, that is the point of the FAT filing system. The SD card can be directly accessed as a file device in the Linux filing system somewhere. dd allows direct copying of blocks, ie it can ignore the FAT filing system. The only PC utilites that I know of that allow direct manipulation of SD cards are Linux based. Technically then the SD card is no longer blank, multiple blocks are used to hold the FAT table entries and directory entries. All the ones I have seen and used will erase and then put some kind of FAT filing system on the SD card. I do not think there any PC utilities that erase a SD card and leave it blank.
Sd secure erase windows#
Does anybody know of a Windows app that allows erasing as opposed to overwriting or wiping?
I could build an Arduino SD card eraser, but would rather find a Windows app that does the same thing - mainly because I think the SDFAT example doesn't go beyond SDHC. I just want the card's controller to recognize the memory as being in the erased state. I want the flash memory to be literally erased, and I don't care if the previous data might somehow be recoverable by the NSA. They talk about "secure erasing" or "wiping", and what they really mean is overwriting the entire card with ones, zeroes or random data, even multiple times. But everything I see for "erasing" an SD card in Windows uses the word in a different way. In fact, in the SDFAT library for Arduino, there is an example called SDFormatter.ino which purports to do exactly that, and the source shows that CMD38 is indeed called. So it appears to be possible to erase a card back to its factory state. Looking through the standard SD card commands, I see CMD38, which supposedly erases a sector or group of sectors.
Presumably such a card is in the erased state other than the areas used to set up FAT32 or other file system. This idea is supported by my understanding that in testing an SD card's performance, testers use a card which is fresh from the factory, and not previously used. Erasing a card might make data logging easier because writes would be faster. I have the idea, from somewhere, that the SD card controller keeps track of which sectors are already erased, and therefore don't have to be erased before writing data to them.
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